In an optical transmission apparatus as an example of an electronic apparatus, a status indicator displays an operation state of a plurality of optical modules connected to each interface card inserted in the optical transmission apparatus is provided in many case. For example, in a portion at which a plurality of optical modules are connected with the status indicator including a green light emitting element, a red light emitting element and an orange light emitting element. The green light emitting element indicates that the optical module is in a normal status in which the optical module can be normally operated. The red light emitting element indicates that the optical module is in an abnormal state in which the optical module can not be normally operated due to a failure or the like. The orange light emitting element indicates that the optical module is in a waiting state such as in an operating test or the like. The red light emitting element, the green light emitting element, orange light emitting element, and the like light emitting element are referred to as a part.
A number of status indicators are arranged on an interface card since a number of optical modules are arranged in a line to the interface card to correspond to each optical module. Specifically, the status indicator is arranged at a front side of a cage to which the optical module is connected. The front side of a cage includes connectors.
When the light emitting element such as an LED is used for the status indicator part itself, it is required to provide one or a plurality of light emitting element to each optical module. However, it is difficult to assure a space for providing the light emitting element at the front side of the cage in the optical transmission apparatus that is highly densified.
Consequently, in the optical transmission apparatus in which the optical modules are highly densified, the cage itself is not equipped with the light emitting element, and the light emitting element such as an LED is mounted on a substrate on which the cage is mounted. Accordingly, a light guide for guiding the light from the light emitting element such as an LED on the substrate to the status indicator part at the front side of the cage is provided outside the cage. The light guide is an elongated transparent plastic component, and is referred to as a light pipe. The light guide can transmit light similarly to an optical fiber.
An end face (light receiving surface) of the light guide at one end side is disposed near the light emitting element, and the light from the light emitting element is introduced into the light guide from the light receiving surface and is emitted from an end surface at the opposite side. Herewith, the end face at the opposite side of the light guide emits the light of the same color as the light emitting element and status indicator is performed. That is, the end face opposite to the right receiving surface of the light guide works as the aforementioned status indicator part.
In the case where the light emitting element emits light of a plurality of colors (for example, LED that emits light of three colors of red, green, and orange), only one light guide is provided to correspond to each optical module. However, since the LED that emits light of a plurality of colors has a large variation in emission color, there is a possibility that the emitting state is misidentified. Consequently, it is preferable that the light emitting element is individually provided to correspond to each of a plurality of colors when the plurality of colors are displayed.
In the case where the light emitting element is individually provided to correspond to each of the plurality of colors, and when operation or non-operation of each optical module is displayed, two light emitting elements are mounted on the substrate with respect to one light guide provided to correspond to each optical module (that is, each connector). Further, when operation, waiting, or non-operation of each optical module is displayed, three light emitting elements are mounted on the substrate with respect to one light guide. Further, since a number of light modules are connected to the cage in the line, the light emitting elements whose number is the same as the number of the optical modules (that is, the number of the light guides) or double or triple number of light emitting elements are closely mounted on the substrate.
In this manner, since the light emitting element is arranged with respect to each of a number of light guides that are closely arranged, the distance between the light emitting elements becomes narrow on the substrate. Particularly, in the optical transmission apparatus that is highly densified, the distance between the light guides becomes narrow, so that the distance between the light emitting elements becomes extremely narrow with it.
As described above, if the distance between the light emitting elements with respect to each of the adjacent light guides becomes narrow, there is a risk that the light from the light emitting element opposing one light guide is introduced into the adjacent light guide. If the upper surface of the light emitting element and the end face (light receiving surface) of the light guide is close to a contact level, leakage of the light into the adjacent light guide can be ignored. However, An actual device structure includes a distance between the upper surface of the light emitting element and the end face (light receiving surface) of the light guide in consideration for a size tolerance for processing or a size tolerance for assembling of a component, so that there is a case that leakage of the light into the adjacent light guide may not be ignored. For example, if red light for the adjacent light guide is leaked and introduced into the light guide transmitting green light, the status indicator emits orange light instead of original green light so as to mix green and red in the light guide. Therefore the status indicator in a different operation state displaying.
As described above, if the distance between the light guides are narrowed, the light form the light emitting element not only introduce into the one light guide in connection with the emitting element but also leak and introduce into an adjacent light guide. Therefore, the user may misidentify color of light at status indicator so as to indicate different color light from the original color.
Herein, in the structure in which light is introduced into each of the adjacent light guides from the adjacent light emitting elements, it has been proposed that a notched part is provided at a coupling unit between the adjacent light guides to scatter the light from the adjacent light emitting element by the notched part, thereby preventing optical leakage (for example, see Japanese Laid-open Utility Model Publication No. 7-32604). Further, in the optical module equipped with a transmission signal light emitting element and a reception signal light emitting element, it has been proposed to provide a partitioning plate having a light shielding property to separate optical pathway of transmission signal light and reception signal light (for example, see Japanese Laid-open Patent Publication No. 2001-116961).
The notched part disclosed in Japanese Laid-open Utility Model Publication No. 7-32604 is provided at the coupling unit in which portions of the adjacent light guides at a rear side of the light receiving surface are integrally connected, and leaked light is scattered by a slope surface of the notched part to prevent introduction into the adjacent light guide. Accordingly, when the coupling unit of the light guides (correspond to light guides) is provided at the rear side of the light receiving surface, leakage of light may be prevented by providing the notched part. However, when the coupling unit of the light guides of the optical transmission apparatus is provided at a front side of the light receiving surface, there is no effect to prevent leakage of light even when the notched part is provided.
Further, the partitioning plate disclosed in Japanese Laid-open Patent Publication No. 2001-116961 is provided to may prevent that transmission signal light is reflected and returned by an end face of one optical fiber and is introduced into the light receiving element, and not to may prevent that the light leaked from the adjacent light emitting element is introduced into the optical fiber. Accordingly, since the structures of the light emitting element and the optical fiber (light guide) are absolutely different, the partitioning plate disclosed in Japanese Laid-open Patent Publication No. 2001-116961 may not be applied to the light guide for the aforementioned optical module.